Uptake and distribution of <sup>14</sup>C-labeled Fosthiazate in tomato (<i>Lycopersicon esculentum</i> L.)

doi:10.4236/as.2011.23041

Paper Menu >>

Journal Menu >>

Vol.2, No.3, 308-312 (2011)

doi:10.4236/as.2011.23041

Agricultural Scienc es

Uptake and distribution of 14C-labeled Fosthiazate in

tomato (Lycopersicon esculentum L.)

Santanu Mukherjee1, Surendra Kumar2, Anjana Srivastava1, Prakash Chandra Srivastava3*

1Department of Chemistry, College of Basic Science & Humanities, G.B. Pant Universi ty of Agricu lt ur e an d Technology, U.S. Na gar,

India;

2Radiations and Isot o p ic Tracers Lab o r a to ry, G.B. Pant University of Agriculture and Technology, U.S. Nagar, India;

3Department of Soil Science, G.B. Pant university of Agri c u lture & Technology, U.S. Nagar, India; *Correspo nding Author:

pcsriv@yahoo.com

Received 13 August 2010; revised 23 May 2011; accepted 21 July 2011.

ABSTRACT

The uptake of 14C-labeled fosthiazate (0.75 mg·L–1)

by tomato plant s was studied in solution culture

both in the presence or absence of 2,4-dinitro-

phenol (DNP, 1 × 10–2 mM), a metabolic inhibitor.

Fosthiazate was rapidly taken up by tomato

plants and nearly one third of the finally ab-

sorbed quantity was taken up in the first half an

hour. The translocation of fosthiazate to the

shoot part was under metabolic control during

the initial stage of upt ake . The ki netics of up take

both in the presence and absence of DNP con-

formed well to the dual phase than a single

phase. In the presence of DNP, the uptake ca-

pacity (Vmax1) for the initial phase suffered, ap-

proximately three fold reduction occurred in

comparison to the absence of DNP while Vmax2

for the latter phase was statistically similar to

the value observed in the absence of DNP sig-

nifying the metabolic dependence of the initial

uptake phase. Autoradiography indicated that

fosthiazate in the tomato plants tends to accu-

mulate in the roots and at the root-shoot junc-

tion. In shoot, it is accumulated in the older

leaves especially, near the leaf tip an d margins.

Keywords: 14C-Fosthiazate; Uptake; Translocation;

Systemicity; Tomato

1. INTRODUCTION

Fosthiazate [(RS)-S-Sec-bentyle-O-ethyl 2 oxo 1,3-

thiazolidin-3-yl phosphonothioate)] is a relatively new

group non-fumigant, organophosphorus nematicide [1].

Studies in field plots have shown that fosthiazate exhib-

its similar efficacy as that other non-fumigant nemati-

cides against a wide range of plant parasite nematodes,

such as root knot nematode (Meloidogyne spp.), cyst

nematodes (Globodera spp.) and root lesion nematodes

(Pratylenchus spp.) [2]. It also has systemic activity

against various species of insects and mites on the foliar

part. Fosthiazate has been on the market in Japan since

1993 and is currently registered for use on potatoes for

controlling cyst nematodes in th e U.K. [3]. However, no

published data are currently available on the uptake and

translocation of 14C-fosthiazate in tomato. Therefore, the

present study was undertaken to study the uptake and

translocation of (14C) fosthiazate by intact tomato plants

and to examine the metabolic dependence of these proc-

esses.

2. MATERIALS AND METHODS

2.1. Chemicals

The fosthiazate chemical was procured from Shanghai

Institute of Chemical Industry Testing Centre, Shangh ai,

China. Radiolabelled 14C-fosthiazate compound was

procured from BRIT, Mumbai. All necessary chemicals

used in the investigation were procured from E. Merck,

Spectro Chem and Loba Chemicals, India

2.2. 14C Uptake & Distribution through

Solution Culture

Healthy seeds of tomato (var. Pant T-3) were sown in

three plastic trays (45 × 30 × 7.5 cm) filled with washed

quartz sand. After germination, 1/2 (half-strength) Hoag-

land solution was applied on alternate day for 2 weeks

and later the plants were thinned to maintain 30 plants

per tray. Thereafter, Hoagland solution of the full

strength was applied thrice in a week. When the plants

were 40 d old, plastic trays were filled with distilled wa-

ter and plants were gently removed from the trays to

ensure the minimum damage to the roots.

Exactly 150 ml Hoagland solution with or without

DNP (1 × 10–2 mM) were taken in conical flasks of 250

S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312

309309

ml capacity. To each flask 0.5967 ci of 14C-fosthizate

was added except for the control (with no fosthiazate).

The final concentration of fosthiazate in the uptake solu-

tion was 0.75 mg/L. Two-40 d old-tomato plants were

placed in each flask ensuring that their roots were prop-

erly dipped in Hoagland solution. The flasks were im-

mediately tightly wrapped in black carbon paper to keep

roots under dark. Plants were kept under the fluorescent

light with the provision for aerating the solution. Plants

were removed from duplicate flasks at 0.5, 1.0, 2, 4, 6, 8,

12 and 24 h periods. After removal, plants were washed

in ice-cold tap water, Hoagland solution and distilled

water, respectively and soak-dried between blotting pa-

per sheets. One plant was kept for autoradiography and

another was separated in roots and shoot parts and

weighed on an electronic balance.

2.3. Solvent Extractant for Fosthiazate

The weighed root and shoot samples were weighed

and ground separately in the presence of 10 ml of

methanol: water (1:1) using a pestle and mortar. After

grinding, the sample was transferred to a conical flask

(100 ml capacity) using 20 ml methanol and extracted

for 1 h on a mechanical shaker. The contents were fil-

tered using Whatman No. 1 filter paper and 15 ml ex-

tract was passed through a column containing silica gel

(2 g), and 5 g Na2SO4 and leached. The leachate was

stored in glass vials.

2.4. Counting Procedure

One ml of leachate was taken in quartz glass scintilla-

tion vial and 9 ml of d ioxane based scin tillation cocktail

(10 g PPO, 0.25 g POPOP, 100 g naphthalene/L of di-

oxane) was added. Prior to counting each sample was

kept under dark for 10 h for the dark adaptation and to

prevent false counts [4]. Each sample was assayed for

the 14C- labeled fosthiazate activity on a liquid scintilla-

tion counter (Pacard-1600 TR) using the external stan-

dardization method.

2.5. Autoradiographic Techniques

Tomato plants after uptake study were kept in herbar-

ium sheets for drying. These plants were kept under the

X-ray film in the cassettes for 15 d exposure time. Then

negative films were subjected to positive method for

clear visualization of accumulation and translocation of

14C-labeled fos thiazate [5].

3. RESULTS AND DISCUSSION

The data on total amount of fosthiazate absorbed by

the whole plants of tomato at different time intervals

presented in Figure 1 indicated that fosthiazate was rap-

idly taken up by tomato plants and under normal condi-

tions nearly one third of the finally absorbed quantity

was taken up in the first half an hour. The accumulation

of fosthiazate in the tomato plants continued till the last

observation (24 h).

The presence of 2,4-dinitrophenol ( DNP), a metabolic

inhibitor decreased the uptake of fosthiazate by tomato

plants at all time intervals. The values of percent inhibi-

tion in the presence of DNP indicated that the relative

inhibition was initially higher up to 2 h (44.68% to

59.66%) as compared to the later timings.Numerous

investigations showed that carprop amid, a fungicide was

rapidly absorbed and translocated by 14 d old rice seed-

lings in half an hour uptake period [6].

Figure 1. Total uptake of fosthiazate by tomato plants (ug·plant–1)

without or with 2,4-dintrophenol. The numerical values above the his-

tograms indicate percent inhibition in the presence of DNP.

S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312

310

The data on percent distribution of absorbed fosthi-

azate in roots and shoot of tomato plants both with or

without DNP are depicted in Figure 2. Under normal

conditions (without DNP), the absorbed fosthiazate was

easily translocated to the shoot part. However, in the

presence of DNP most of the absorbed fosthiazate was

retained in the roots during the initial stages of uptake

and its translocation to shoo t part was slowed down.

The distributions of radiolabelled fosthiazate in to-

mato roots (at 0.5 h) and in an intact tomato shoot (at 4 h)

are depicted in an autoradiograph (Plate 1). As shown in

the autoradiographs, the absorbed fosthiazate mainly ac-

cumulated in the roots and also at the root-shoot junction.

The retention of fosthiazate in the stem was much lesser

as compared to the leaves. In the shoot, the lower older

leaves accumulated more fosthiazate as compared to the

younger upper leaves. Within the leaf, fosthiazate con-

centrated at the leaf tip and also at leaf margins. The

translocation of fosthiazate appeared to be mediated by

the apoplastic movement which is solely regulated by

physical forces like the transpirational pull and root

pressure and leads to the accumulation of the compound

at the apex and margins of leaves [7-9]. However, the

observed partial inhibition of fosthiazate accumulation in

the shoot in the presence of a metabolic inhibitor like

DNP indicated that the translocation of absorbed fosthi-

azate to the shoot was partly dependent on the metabo-

lism.

Plate 1. Radioautographs of 14C-fosthiazate exposed tomato

roots (A, after 0.5 h) and whole plant (B, after 24 h).

Time dependent kinetics of fosthiazate uptake by to-

mato plants both in the presence and absence of DNP

was examined by using a modified Langmuir type equa-

tion (Equatio n 1).

max max

11 .

qVV t

 1

(1)

where,

q = amount of 14C fosthiazate taken up by plant at

time ‘t’;

Vmax = ma ximum absorption of 14 C fosthiazate/ plant;

B = a constant;

T = time (h).

The uptake data of fosthiazate by tomato plants were

fitted to the Equation 1 by plotting the reciprocals of

Figure 2. Percent distribution of fosthiazate between roots and shoot under both without and with DNP.

S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312

311311

amount of fosthiazate (µg·plant–1) absorbed by plants at

a given time against time (h) (Figure 3). Assuming that

the kinetics of fosthiazate was governed by a single

phase, the values of Vmax, B and the coefficients of de-

termination (R2) for single phase were computed. How-

ever, a close perusal of the distribution of the points in

Figure 3 revealed that the uptake kinetics could be

splitted into two distinct straight line parts; the first

phase up to 2 h and the second one which appeared to

operate beyond 2 h onward upto 24 h. The data of both

the phases were fitted individually to the Equation 1.

The computed values of Vmax, B and R2 for both the

single and dual phases for tomato plant are presented in

Tabl e 1. Statistically sig nificant values of R2-value indi-

cated that the uptake data conformed to the kinetic equa-

tion used in the study. A comparison to R2-values for the

single and dual uptake phases revealed that the dual

phase could account the uptake pattern of fosthiazate by

tomato plants better than single phase both in the pres-

ence and the absence of DNP. In the presence of DNP,

the value of Vmax for the initial phase suffered a signifi-

cant drastic (roughly three fold) reduction in comparison

to the absence of DNP. On the other hand, the value of

Vmax for the latter phase in the presence of DNP was sta-

tistically similar to the value observed in the absence of

DNP. This clearly indicated that the initial uptake of

fosthiazate by tomato plants was under metabolic con-

trol.

In conclusion, this study showed that uptake of fost-

hiazate, a nematicide, by tomato plants was quite rapid

Table 1. Kinetic parameters of single and dual phase uptake of

fosthiazate by roots and shoots of tomato plants with and

without 2,4-dinitrophenol (DNP).

Model Parameters Without DNP With DNP

Vmax 2.786 1.544

B 0.931 1.050

Single phase

R2 0.949** 0.751*

Vmax1 2.214 0.749

B1 0.598 1.680 Dual phase (I)

R12 0.999** 0.991*

Vmax2 3.731 3.3934

B2 3.323 11.565 Dual phase (II)

R22 0.926 0.994

**significant at p = 0.01 and *significant at p = 0.05.

suiting to its application through irrigation water. The

kinetics of uptake both in the presence or absence of

DNP conformed well to the dual phase than a single

phase. The initial phase of uptake was under metabolic

control. The initial translocation of fosthiazate to the

shoot part was inhibited by metabolic inhibitor. In the

tomato plants, fosthiazate tends to accumulate more in

the roots and at the root-shoot junction. In shoot, it is

accumulated in the older leaves especially, near the leaf

tip and margins.

4. ACKNOWLEDGEMENT

The authors are highly indebted to university authority for providing

Figure 3. A plot of 1/q versus 1/t single and dual phase uptake of Fosthiazate by whole tomato plant. **Signifi-

cant at p = 0.01, *Significan t a t p = 0.05.

S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312

312

necessary facilities.

REFERENCES

[1] Koyanagi, T., Imai, O. and Yoshida, K. (1998) Develop-

ment of a new nematicide, fosthiazate. Journal of Pesti-

cide Science, 23, 174-177.

[2] Ingham, R.E., Hamm, P.B., Williams, R.E. and Swanson,

W.H. (2000) Control of Meloidogyne chitwoodi in potato

with fumigant and nonfumigant nematicides. Journal of

Nematology, 32, 556-558.

[3] Sturz, A.V. and Kimpinski, J. (1999) Effects of fosthi-

azate and aldicarb on populations of plant growth pro-

moting bacteria, root lesion nematodes and bacteria-

feeding nematodes in the root zone of potatoes. Plant

Pathology, 48, 26-32.

doi:10.1046/j.1365-3059.1999.00305.x

[4] Horrock, D.L. (1974) Applications of liquid scintillation

counting. Academic Press, New York, 331.

[5] John, D.H.O. and Field, G.T.J. (1963) A text book of

photographic chemi st ry. Chapman and Hall, London, 29.

[6] Rohilla, R., Singh, U.S. and Singh, R.L. (2001) Mode of

action of acibenzolar-S-Methyl against sheath blight of

rice, caused by Rhizoctonia solani Kuhn. Pest Manage-

ment Science, 58, 63-66. doi:10.1002/ps.423

[7] Crowdy, S.H. (1977) Translocation in systemic fungi-

cides in Book Systemic. In: Marsh, R., Ed., Fungicides,

2nd Edition, Longmann Ltd, New York, 92-114.

[8] Hammett, K.R.W. (1968) Root application of systemic

fungicides for control of powdery mildews. Plant Dis-

ease Report, 52, 754-760.

[9] Singh, U.S., Kumar, J. and Tripathi, R.K. (1985) Uptake,

translocation, distribution and persistence of 14C-meta-

xyl in pea (Pisum sativum) Z. Pflanzenkrankh Pflanzen-

schutz, 92, 64-67.